Development of a PCR-based assay for diagnosis of Pneumocystis pneumonia. A simple, yet efficient, DNA extraction and amplification protocol has been developed, permitting this assay to be carried out in a single day on the Clinical Microbiology Laboratory. A prospective study is currently underway comparing PCR with FA for detection pf Pneumocystis in respiratory specimens, and preliminary data indicates that the PCR assay can improve the efficiency of diagnosis, specially for induced sputa. Of 160 specimens so far analyzed: 16 were PCR+/FA+; 6 were PCR+/FA- (all were sputum, subsequently confirmed), 0 were PCR-/FA+; 138 were PCR-/FA-. Work is currently underway to develop an ELISA-type assay for detection of the PCR product.